Meiosis in barley: manipulating crossover frequency and distribution (LOLA)

英国农业未来的可持续性将取决于能否提供能够满足未来环境和经济需求的新作物品种。通过植物育种开发新作物品种的基础是利用有性繁殖和选择性杂交过程产生的自然变异，以产生具有理想特性的新颖组合的品系。在雄配子和雌配子的形成过程中，个体遗传的亲本基因的新组合是通过减数分裂过程产生的。在减数分裂中，同源重组确保染色体被准确分离，从而使每个配子获得一套完整的染色体。为了实现这一点，必须在同源的亲本染色体对之间建立瞬时的物理联系。这导致了每对同源双亲染色体之间的遗传信息的相互交换，从而沿着每条染色体产生了新的基因组合。因此，当雄配子和雌配子在有性繁殖过程中融合时，后代具有各自亲本的一些特征，以及在减数分裂重组过程中通过基因的“洗牌”而出现的新特征。因此，在植物减数分裂过程中控制染色体上的重组模式是决定植物育种计划结果的主要因素之一。不幸的是，很明显，重组的模式可能会高度扭曲，以至于基因组某些区域的基因很少进行重组。在一些重要的草类物种，如大麦和小麦中就是这种情况，它可能会对潜在的育种计划产生不利影响。在过去的十年里，对拟南芥--植物遗传学的模式系统--的研究，在我们对植物减数分裂和重组如何在分子水平上进行控制的理解方面取得了相当大的进展。因此，该项目寻求将这些知识中的一部分转移到作物大麦上，从而使植物育种者能够克服他们在开发这种作物的新品种时面临的主要挑战之一。对于大麦来说，这是可行的，因为我们对大麦遗传学有很好的了解，而且这种作物的遗传工具已经到位，以促进这种转移。我们的目标将是确定大麦减数分裂重组是如何控制的，以及重组模式扭曲的基础。然后，我们将探索可以用来操纵重组模式的策略，这些策略可以被植物育种者在其现有计划中应用，而不需要求助于转基因技术。如果这是成功的，那么这些方法可以应用于更复杂的牧草作物物种，如小麦和牧草(例如黑麦草)，它们表现出相同的倾斜重组分布。

The future sustainability of UK agriculture will be dependent on the provision of new crop varieties that are able to meet future environmental and economic needs. The development of new crop varieties by plant breeding is based on harnessing the natural variation that is generated through the process of sexual reproduction and selective crossing to produce lines with novel combinations of desirable characteristics. During the formation of male and female gametes new combinations of the parental genes inherited by an individual are generated through the process of meiosis. In meiosis, homologous recombination ensures that chromosomes are accurately segregated such that each gamete gets a single complete set of chromosomes. To achieve this, transient physical links must be established between homologous pairs of parental chromosomes. This results in the reciprocal exchange of genetic information between each pair of homologous parental chromosomes, thereby generating a new combination of genes along each chromosome. Thus when male and female gametes fuse during sexual reproduction the progeny possess some characteristics of each parent and novel features that have arisen through the 'shuffling' of genes during meiotic recombination. Control of the patterns of recombination along chromosomes during meiosis in plants is therefore one of the major factors determining the outcome of plant breeding programmes. Unfortunately, it is clear that patterns of recombination can be highly skewed such that genes in some regions of the genome rarely undergo recombination. This is the case in some important grass species such as barley and wheat where it can have an adverse effect on potential breeding programmes Over the past decade studies in Arabidopsis, the model system for plant genetics, have resulted in considerable progress in our understanding of how meiosis and recombination in plants is controlled at the molecular level. Hence, this project seeks to transfer some of this knowledge to the crop plant barley and thus enable plant breeders to overcome one of the major challenges they face in the development of new varieties of this crop. This is feasible in the case of barley because we have a good understanding of barley genetics and genetic tools are in place for this crop to facilitate such a transfer. Our objectives will be to determine how meiotic recombination is controlled in barley and the basis for the skewed pattern of recombination. We will then explore strategies that could be used to manipulate the patterns of recombination that could be applied by plant breeders in their existing programmes without recourse to GM technology. If this is successful these approaches could then be applied to more complex grass crop species such as wheat and forage grasses (e.g. ryegrass) that show the same skewed distribution of recombination.